WASHINGTON - In their strongest statement yet on the Columbia disaster, investigators said Tuesday that flyaway foam from the fuel tank was "the most probable cause" of the wing damage that brought down the space shuttle almost five months ago.
"We've been trying to line up all the Swiss cheese holes. I think those holes have lined up pretty good," said Roger Tetrault, a member of the Columbia Accident Investigation Board.
Tetrault said he believes the deadly breach was part way down the leading edge of Columbia's left wing, at or near carbon panel No. 8. The engineering analysis as well as the shuttle wreckage pinpoints that location, he said. That is the spot - or close to it - where a 11/2-pound chunk of foam insulation from the external fuel tank struck during liftoff back in January.
"When you put all of those pieces of Swiss cheese together, it's a pretty compelling story that, in fact, the foam is the most probable cause of the shuttle accident," said Tetrault, a retired corporate executive who used to build nuclear submarines.
It was the first time any of the 13 board members, publicly at least, blamed the foam for the Feb. 1 disaster. All seven astronauts aboard were killed.
Also on Tuesday, NASA released video and photographs of the crew salvaged from the 85,000 pounds of wreckage. They showed the five men and two women posing for official portraits, playing with objects in weightlessness and demonstrating daily routines like shaving and brushing teeth.
Now that they have determined the most probable cause of the disaster, the investigators are struggling with how best to express the finding in their final report, expected to be released by the end of July.
"The board will have to decide what word we want to use," said the board's chairman, retired Navy Adm. Harold Gehman Jr. "Do we want to say, "We think it did, we're sure it did, it might of, we think most likely it did, the board is confident?'
"I have 13 different opinions on that, and at some time I'm going to have to lock everybody in a room and come out with one set of words," he said.
Gehman expects to release an interim recommendation to NASA soon, possibly as early as this week, that will emphasize the need for caution to avoid damage to the wings' thermal protection shielding on every flight and to repair problems in orbit.
"The board is trying to craft words which will force NASA to do something," he said.
Gehman said half the final report will focus on NASA management and culture. The other half will involve technical matters, most notably the loss of foam from space shuttle external fuel tanks during every launch.